ICD-10 Code C90.31 – Solitary plasmacytoma in remission (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C90.31 – Solitary plasmacytoma in remission
What it is
C90.31 identifies a history of solitary plasmacytoma that is currently in remission. Use it when the condition was previously diagnosed and is no longer active, but remains clinically relevant.
Clinical signs
Clinical features vary; refer to documentation. Records may note prior localized plasma cell tumor, treatment response, and absence of active disease on follow-up evaluation.
When to use this code
Use this code when the provider documents solitary plasmacytoma in remission, including follow-up visits after treatment. It is appropriate when the diagnosis is still being monitored, but there is no evidence of active disease. Check documentation if remission status is unclear.
Do not use for
Do not use C90.31 for active solitary plasmacytoma, multiple myeloma, or uncertain plasma cell disorders. If the record does not clearly state remission, code the documented current condition instead.
Coding tip
Verify that “in remission” is explicitly documented before assigning C90.31.